[1] It's Official: La Niña Will Stay For Winter

Think rain and plenty of snow next winter for Northwest watersheds--that's the Aug. 5 prognosis from NOAA's Climate Prediction Center.

The agency has officially announced the onset of a La Niña episode after the equatorial Pacific has been cooling for months, ever since the moderate El Niño peaked last year. The ocean is expected to cool even more over coming months.

But the agency says signals are mixed about the potential strength of the coming cool period.

NOAA says most of its dynamical models predict a moderate-to-strong episode, while most statistical models point to a weaker one. In any case, in the Northwest, it's expected to pick up steam later this fall, and to last through early 2011.

In other parts of the country, its effects will likely be felt sooner.

Changes to wind patterns in the Gulf of Mexico are likely to increase the number of hurricanes there over the next two months.

But east of the International Date Line, the top 300 meters of the eastern equatorial Pacific holds a deep layer of below-average-temperature water.

Typical of a La Niña, NOAA reported, convection was enhanced over Indonesia, but remained suppressed over the western and central tropical Pacific, along with enhanced low-level easterly trade winds and anomalous upper-level westerlies over the western and central equatorial Pacific.

The Australians agree.

The Aug. 2 El Niño-Southern Oscillation wrap-up from the Australian Bureau of Meteorology said, "All indicators in the Pacific Ocean show that we are now in the early stages of a La Niña event. Computer models predict the central Pacific will continue to cool in coming months, indicating some further strengthening of the event is likely."

They also reported that in some regions, the sub-surface water was more than 3 C cooler than average in July.

Sea surface temperatures are already 1-3 F colder than average off the Washington and Oregon coasts, where a large body of water of more average temperature lies farther offshore.

Albacore tuna, which like to travel along edges between warm and cool currents, have been caught 20-40 miles off the Oregon coast in recent weeks, along with a few bluefin and yellowtail.

Closer to shore, salmon fishing has picked up considerably, north of the Columbia River for returning fall chinook.

Nearly 700,000 are expected to return to the Columbia this year. Most returning adults headed to sea in 2007, a year of relatively good ocean conditions, but nothing like the productive regime of 2008 that occurred during the last La Niña, which helped produce this year's excellent spring chinook run, the third highest in the Columbia since 1938.

This year's sockeye run also went to sea in 2008 and returned this year--setting a new record since biologists began counting them in 1938 after Bonneville Dam was completed.

Researchers have said all spring that La Niña-like conditions seemed to be brewing off the Northwest coast, but upwelling had been spotty due to lingering southerly winds.

However, by the end of July, upwelling had generally improved, chlorophyll levels were rising in the ocean, and sea surface temperatures off the mouth of the Columbia are 4°F cooler than last year at this time. -Bill Rudolph

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